San Mateo County Weather in December
Average highs run from 60°F on December 1 to 59°F on December 31, and lows from 43°F to 43°F. Normal precipitation for the month is 5.17 in over about 13 wet days.
December day by day
The normal high and low for each date, and the record, in °F.
- Normal low
- Normal high
- Record high
- Record low
December at a glance
- Average high
- 59°F
- Average low
- 43°F
- Precipitation
- 5.17 in
- Record high
- 76°FDec 12, 1958
- Record low
- 18°FDec 12, 1932
- Chance of a freeze
- 48%
- Daylight
- 9 h 47 min to 9 h 37 min
- Cloud cover
- 58%
- Humidity
- 81%
- Dew point
- 46°F
- Wind
- 10.5 mph
Every day of the month
A wet day has at least 0.01 inch of precipitation.
| Date | Normal high | Normal low | Record high | Record low | Chance wet |
|---|---|---|---|---|---|
| Dec 1 | 60°F | 43°F | 73°F 1943 | 30°F 1931 | 41% |
| Dec 2 | 60°F | 43°F | 75°F 1941 | 30°F 1936 | 42% |
| Dec 3 | 60°F | 43°F | 73°F 1959 | 28°F 1936 | 42% |
| Dec 4 | 60°F | 43°F | 74°F 1958 | 28°F 1936 | 42% |
| Dec 5 | 60°F | 43°F | 73°F 1976 | 27°F 2013 | 42% |
| Dec 6 | 59°F | 43°F | 75°F 2024 | 28°F 1931 | 42% |
| Dec 7 | 59°F | 43°F | 75°F 1934 | 22°F 1998 | 42% |
| Dec 8 | 59°F | 43°F | 75°F 2024 | 25°F 1978 | 42% |
| Dec 9 | 59°F | 43°F | 74°F 1934 | 22°F 1972 | 42% |
| Dec 10 | 59°F | 43°F | 71°F 1934 | 25°F 1972 | 43% |
| Dec 11 | 59°F | 43°F | 72°F 1958 | 23°F 1932 | 43% |
| Dec 12 | 59°F | 43°F | 76°F 1958 | 18°F 1932 | 43% |
| Dec 13 | 59°F | 43°F | 70°F 1953 | 19°F 1932 | 43% |
| Dec 14 | 59°F | 43°F | 71°F 1958 | 22°F 1932 | 43% |
| Dec 15 | 59°F | 43°F | 72°F 1980 | 20°F 1932 | 43% |
| Dec 16 | 59°F | 43°F | 74°F 1998 | 26°F 1932 | 43% |
| Dec 17 | 59°F | 43°F | 73°F 1958 | 27°F 1965 | 43% |
| Dec 18 | 59°F | 43°F | 70°F 1998 | 27°F 1965 | 43% |
| Dec 19 | 59°F | 43°F | 70°F 1999 | 29°F 1935 | 43% |
| Dec 20 | 59°F | 43°F | 71°F 1944 | 28°F 1965 | 43% |
| Dec 21 | 59°F | 43°F | 70°F 1999 | 24°F 1968 | 43% |
| Dec 22 | 59°F | 43°F | 68°F 1999 | 19°F 1990 | 43% |
| Dec 23 | 59°F | 43°F | 69°F 2014 | 21°F 1990 | 43% |
| Dec 24 | 59°F | 43°F | 72°F 2013 | 22°F 1990 | 43% |
| Dec 25 | 59°F | 43°F | 75°F 1967 | 25°F 1998 | 43% |
| Dec 26 | 59°F | 43°F | 74°F 1967 | 25°F 1998 | 44% |
| Dec 27 | 59°F | 43°F | 75°F 1967 | 28°F 1990 | 44% |
| Dec 28 | 59°F | 43°F | 74°F 1967 | 26°F 1930 | 44% |
| Dec 29 | 59°F | 43°F | 72°F 2025 | 22°F 1930 | 44% |
| Dec 30 | 59°F | 43°F | 69°F 1958 | 24°F 1930 | 44% |
| Dec 31 | 59°F | 43°F | 70°F 1958 | 28°F 1990 | 45% |
Chance of rain
- Chance of a wet day
Sunrise and sunset
Times for 2026, local time (PST).
- December 1
- sunrise 7:05 AM, sunset 4:52 PM
- December 31
- sunrise 7:24 AM, sunset 5:01 PM
Other months
Sources
Normals: NOAA NCEI U.S. Climate Normals, 1991-2020, station USC00043714 (Half Moon Bay), public domain. Records: NOAA GHCN-Daily, station USC00047339, every year on file, quality-flagged values removed. Cloud, humidity, wind and sunshine: NASA POWER (MERRA-2, CERES and GEWEX SRB), 1991-2020. The data was obtained from the National Aeronautics and Space Administration (NASA) Langley Research Center's Prediction Of Worldwide Energy Resources (POWER) project funded through the NASA Earth Science Division: POWER Daily API v2, accessed 2026-09-24. Sun and moon: computed with the NOAA solar equations and Meeus.